Semiconductor module and inverter device

ABSTRACT

A semiconductor module includes a base plate; a plurality of substrates placed on one surface of the base plate, with each substrate of the plurality of substrates including a switching element, a diode element, and a connection terminal area; and a parallel flow forming device that forms parallel coolant flow paths that are provided so as to be in contact with the other surface of the base plate. The coolant flow paths are formed such that coolant flows in a coolant flow direction.

CROSS-REFERENCE TO RELATED APPLICATION

The disclosure of Japanese Patent Application No. 2007-135682 filed onMay 22, 2007 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a semiconductor and an inverter device.

There exists an inverter circuit for driving an electric motor of ahybrid vehicle, an electric vehicle, or the like. A semiconductor modulethat includes a switching element that forms the inverter circuit has ahigh heating value, and furthermore, requires downsizing. Therefore, awater-cooling system is often used as a cooling structure of thesemiconductor module. As the configuration of the semiconductor modulehaving such a water-cooling system, Japanese Patent ApplicationPublication No. JP-A-2004-349324 (pages 6 and 7, and FIG. 5) discloses aconfiguration shown in FIGS. 15A, 15B and 15C for example. FIG. 15A is aplan view, FIG. 15B is a side view, and FIG. 15C is an elevational view.A semiconductor module 101 shown in FIGS. 15A, 15B and 15C includes abase plate 102 in which a fin 103 in stripe form is formed on a backsurface, and six substrates 104 placed on an upper surface of the baseplate 102. On the lower surface of the base plate 102, a water pathcover (not shown) is provided to contact a bottom surface of the fin 103(surface on a lower side of the fin 103 in FIG. 15B), whereby eachcoolant flow path 105 is formed between the plurality of fins 103.Therefore, in the semiconductor module 101, a coolant flow direction Dis the longitudinal direction (horizontal direction in FIG. 15B) of thebase plate 102. Six substrates 104 placed on the base plate 102 arearranged in line in the coolant flow direction D.

On each substrate 104, two each of an insulated gate bipolar transistor(IGBT) element as a switching element 106 and a diode element 107 arearranged. A connection terminal area 108, in which a wire bonding forelectrically connecting the elements 106 and 107 and a control substrate(not shown) on each substrate 104 is performed, is arranged adjacent toeach substrate 104. On the substrate 104, two switching elements 106 andtwo diode elements 107 are arranged alternately in line in aperpendicular direction with respect to the coolant flow direction D.The connection terminal area 108 is arranged on a side opposite to aside in which a pair of substrates 104A and 104B faces each other in thecoolant flow direction D.

SUMMARY

In the configuration of the semiconductor module shown in FIG. 15Adescribed above, all six substrates 104 are arranged in line in thecoolant flow direction D. Therefore, a single flow of the coolantthrough each coolant flow path 105 formed between the plurality of fins103 sequentially cools the plurality of (at least three) switchingelements 106. Accordingly, there has been a problem in that thetemperature of the coolant flowing through each coolant flow path 105gradually rises, whereby the cooling performance for the switchingelement 106 on the downstream side decreases.

In addition, in the configuration of the semiconductor module shown inFIG. 15A described above, the connection terminal area 108 is arrangedon the side opposite to the side in which the pair of substrates 104Aand 104B face each other in the coolant flow direction D. Thus, sincethe switching element 106 of each of the pair of substrates 104A and104B face each other without the connection terminal area 108 therebetween, the switching elements 106 that generate most of the heat oneach substrate 104 are arranged in positions relatively close to eachother. Therefore, a thermal interference by heat transmitted from theplurality of switching elements 106 easily occurs on the base plate 102,whereby a local temperature rise of the base plate 102 may occur. Inthis case, the cooling performance for the switching element 106arranged in a high-temperature region of the base plate 102 maydecrease.

The present invention provides a semiconductor module and an inverterdevice having a configuration that can suppress a thermal interferenceon a base plate caused by heat of a switching element included in eachof a pair of substrates and thereby appropriately cool the switchingelement of all substrates. The present invention can also achievevarious other advantages.

According to an exemplary aspect of the invention, a semiconductormodule includes a base plate; a plurality of substrates placed on onesurface of the base plate, with each substrate of the plurality ofsubstrates including a switching element, a diode element, and aconnection terminal area; and a parallel flow forming device that formsparallel coolant flow paths that are provided so as to be in contactwith the other surface of the base plate. The coolant flow paths areformed such that coolant flows in a coolant flow direction. Theswitching element and the diode element are arranged in line in aperpendicular direction with respect to the coolant flow direction. Theswitching element and the connection terminal area are arranged inpositions differing in the coolant flow direction in each of thesubstrates. A pair of substrates of the plurality of substrates isarranged in series in the coolant flow direction. The switching elementof one of the substrates of the pair of substrates is arranged on oneside in the perpendicular direction, and the diode element of the othersubstrate of the pair of substrates is arranged on the one side in theperpendicular direction. The connection terminal area of at least onesubstrate of the pair of substrates is arranged closer to a side that isbetween the pair of substrates with respect to the switching element ofthe at least one substrate of the pair of substrates.

According to an exemplary aspect of the invention, a semiconductormodule includes a base plate; a plurality of substrates placed on onesurface of the base plate, with each substrate of the plurality ofsubstrates including a switching element, a diode element, and aconnection terminal area; and a parallel flow forming device that formsparallel coolant flow paths that are provided so as to be in contactwith the other surface of the base plate. The coolant flow paths areformed such that coolant flows in a coolant flow direction. Theswitching element and the diode element are arranged in line in aperpendicular direction with respect to the coolant flow direction. Theswitching element and the connection terminal area are arranged inpositions differing in the coolant flow direction in each of thesubstrates. A pair of substrates of the plurality of substrates isarranged in series in the coolant flow direction. The connectionterminal area is arranged on a first side in the perpendicular directionfor one substrate of the pair of substrates and on a second side in theperpendicular direction for the other substrate of the pair ofsubstrates. The diode element is arranged on the second side in theperpendicular direction for the one substrate of the pair of substratesand on the first side in the perpendicular direction for the othersubstrate of the pair of substrates. The connection terminal area of atleast one substrate of the pair of substrates is arranged closer to aside that is between the pair of substrates with respect to theswitching element of the at least one substrate of the pair ofsubstrates.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the invention will be explained withreference to the drawings, wherein:

FIG. 1 is a plan view showing the configuration of a main section of asemiconductor module according to a first embodiment of the presentinvention;

FIG. 2 is a sectional view along line II-II of FIG. 1;

FIG. 3 is a sectional view along line III-III of FIG. 1;

FIG. 4 is a sectional view along line IV-IV of FIG. 2;

FIG. 5 is a sectional perspective view of the semiconductor moduleaccording to the first embodiment of the present invention;

FIG. 6 is a wiring diagram of an inverter circuit according to the firstembodiment of the present invention;

FIG. 7 is a plan view showing the entire configuration of thesemiconductor module according to the first embodiment of the presentinvention;

FIG. 8 is a sectional view along line VIII-VIII of FIG. 7;

FIG. 9 is a plan view showing the configuration of a main section of asemiconductor module according to a second embodiment of the presentinvention;

FIG. 10 is a plan view showing the configuration of a main section of asemiconductor module according to a third embodiment of the presentinvention;

FIG. 11 is a plan view showing the configuration of a main section of asemiconductor module according to a fourth embodiment of the presentinvention;

FIG. 12 is a plan view showing the configuration of a main section of asemiconductor module according to a fifth embodiment of the presentinvention;

FIG. 13 is a diagram showing an example according to another embodimentof the present invention, in which two semiconductor modules havingdifferent heating values are arranged in line in a coolant flow pathdirection;

FIG. 14 is a diagram showing an example of the arrangement of twosemiconductor modules according to another embodiment of the presentinvention; and

FIGS. 15A, 15B and 15C are diagrams showing the configuration of aconventional semiconductor module.

DETAILED DESCRIPTION OF EMBODIMENTS 1. First Embodiment

A first embodiment of the present invention will be described accordingto the drawings. In this embodiment, an example in which the presentinvention is applied to a semiconductor module 1 as an inverter deviceforming a three-phase AC inverter circuit will be described. FIG. 1 toFIG. 8 are diagrams for illustrating the configuration of thesemiconductor module 1 according to this embodiment. Note that theconfiguration above a base plate 2 is omitted, with the exception of asubstrate 3, in FIG. 1 to FIG. 5.

As shown in the drawings, the semiconductor module 1 has a coolingstructure including a coolant flow path 7 for cooling the substrate 3placed on an upper surface 2A of the base plate 2, particularly aswitching element 4 having the highest heating value. As shown in FIG.6, the semiconductor module 1 forms an inverter circuit 11 for driving athree-phase AC electric motor 31. Therefore, as shown in FIG. 1, sixsubstrates 3, each including the switching element 4 and a diode element5, are placed on the upper surface 2A of the base plate 2. Further, inthe semiconductor module 1, as shown in FIG. 7 and FIG. 8, a case 41 isplaced so as to surround six substrates 3 on the base plate 2, and acontrol substrate 9 for an operation control and the like of theswitching element 4 on each substrate 3 is supported by the case 41. Theconfiguration of each section of the semiconductor module 1 will bedescribed below in detail.

1-1. Cooling Structure of Substrate

First, the cooling structure of the substrate 3 in the semiconductormodule 1 will be described according to FIG. 1 to FIG. 5. As shown inFIG. 1, the semiconductor module 1 includes the base plate 2, sixsubstrates 3 placed on the upper surface 2A of the base plate 2, and acoolant flow path 7 provided to contact a lower surface 2B of the baseplate 2. In the coolant flow path 7, a plurality of fins 8 is providedas a parallel flow formation unit that forms parallel flows of thecoolant in a specific direction. As shown in FIG. 2 to FIG. 5, theplurality of fins 8 are arranged to be parallel with each other alongthe lower surface 2B of the base plate 2. Each fin 8 is formed in aplate shape having a specific thickness and provided perpendicular tothe lower surface 2B of the base plate 2, and is formed integrally withthe base plate 2 by a cutting process and the like of the lower surface2B of the base plate 2. The intervals between the plurality of fins 8are approximately constant, and the height of the plurality of fins 8 isalso constant. With the fin 8 being provided in this manner, the flow ofthe coolant introduced into the coolant flow path 7 becomes a parallelflow which is parallel with a direction defined by the parallel flowformation unit, i.e., a direction along the fin 8. In the example shownin the drawings, flows of the coolant parallel with each other areformed between the plurality of fins 8. As shown in FIG. 1, thedirection parallel with the plurality of fins 8 (upward direction inFIG. 1) is the coolant flow direction D. The direction perpendicular tothe coolant flow direction D is a perpendicular direction C with respectto the coolant flow direction (horizontal direction in FIG. 1,hereinafter referred to simply as “perpendicular direction C”). Notethat, in this embodiment, the upper surface 2A of the base plate 2corresponds to one surface of the present invention and the lowersurface 2B corresponds to the other surface of the present invention.

As shown in FIG. 2, FIG. 3 and FIG. 5, the base plate 2 is supported bya water path formation member 12. A bottom plate member 13 in a flatplate shape is provided to cover the bottom surface of the water pathformation member 12. The water path formation member 12 externally has arectangular parallelepiped form in which the planar shape isapproximately the same as that of the base plate 2. The water pathformation member 12 has a circumference wall 12 a surrounding the outercircumference thereof, a contact plate section 12 b formed on the innerside of the circumference wall 12 a and a partition wall 12 c. The uppersurface of the circumference wall 12 a is in contact with the lowersurface 2B of the base plate 2, and the lower surface of thecircumference wall 12 a is in contact with the bottom plate member 13.The contact plate section 12 b is a plate-shaped section provided so asto contact the bottom surface of the fin 8 (lower surface in FIG. 2 andFIG. 3). Thus, the coolant flow path 7 is formed of each a plurality oflong spaces surrounded by the plurality of fins 8 and the contact platesection 12 b. Therefore, the plurality of parallel flows of the coolantis formed by the coolant flowing through each of the plurality ofcoolant flow paths 7 partitioned by the plurality of fins 8. Thepartition wall 12 c is a wall-shaped member that is provided along theperpendicular direction C and partitions the space below the contactplate section 12 b into two spaces. The space on the right side of thepartition wall 12 c in FIG. 3 and FIG. 5 is an inflow side coolantreservoir 14A and the space on the left side of the partition wall 12 cis an outflow side coolant reservoir 14B.

The inflow side coolant reservoir 14A is connected with the coolant flowpath 7 via an inflow side reducer section 15A, and the outflow sidecoolant reservoir 14B is connected with the coolant flow path 7 via anoutflow side reducer section 15B. The inflow side reducer section 15Aand the outflow side reducer section 15B are formed by a gap between theperipheral wall 12 a and the contact plate section 12 b of the waterpath formation member 12. As shown in FIG. 4, the inflow side reducersection 15A and the outflow side reducer section 15B are both openingsections having a long slit shape in the perpendicular direction C. Theinflow side coolant reservoir 14A, the outflow side coolant reservoir14B, the inflow side reducer section 15A, and the outflow side reducersection 15B all have the same length in the perpendicular direction C asa full width W of the coolant flow path 7.

The coolant flows in a manner described below. That is, as shown in FIG.4, the coolant enters from an inflow path 16A, and is carried to theinflow side coolant reservoir 14A by an outlet pressure and the like ofa pump (not shown). The coolant filled in the inflow side coolantreservoir 14A passes through the inflow side reducer section 15A andflows in the coolant flow path 7 between the plurality of fins 8, asshown in FIG. 3 to FIG. 5. When passing through the coolant flow path 7,the coolant performs the heat exchange with the base plate 2 and the fin8, whereby the substrate 3 on the base plate 2 is cooled. The coolant,which has passed through the coolant flow path 7, passes through theoutflow side reducer section 15B to be sent to the outflow side coolantreservoir 14B. Then, the coolant filled in the outflow side coolantreservoir 14B passes through an outflow path 16B to be discharged. Asdescribed above, the coolant flow direction D in the coolant flow path 7is a direction parallel with the plurality of fins 8. In order for thecoolant to efficiently perform the heat exchange with the base plate 2and the fin 8, the base plate 2 and the fin 8 are preferably formed ofmetal having high thermal conductivity (such as copper, for example). Inthis embodiment, a cooling liquid used for a vehicle, in which ethyleneglycol and the like are added to water and the like is used as thecoolant.

1-2. Arrangement Configuration of Substrate

Next, the arrangement configuration of the substrate 3 in thesemiconductor module 1, which is the main section in the presentinvention, will be described according to FIG. 1. In this embodiment,six substrates 3 are arranged on the upper surface 2A of the base plate2, such that two substrates 3 are aligned in line in the coolant flowdirection D and three substrates 3 are aligned in line in theperpendicular direction C. Those six substrates 3 form the invertercircuit 11 as described below.

The substrate 3 includes a lower arm substrate 3A having a lower armswitching element 4A forming a lower arm 33, and an upper arm substrate3B having an upper arm switching element 4B forming an upper arm 34 ofthe inverter circuit 11 (see FIG. 6). Among six substrates 3, threesubstrates arranged on the downstream side (upper side in FIG. 1) of thecoolant flow direction D is the lower arm substrate 3A, and threesubstrates arranged on the upstream side (lower side in FIG. 1) of thecoolant flow direction D is the upper arm substrate 3B. Six substrates 3are arranged as three sets of substrates 3 aligned in the perpendiculardirection C, each set being formed of (a pair of) the lower armsubstrate 3A and the upper arm substrate 3B as a pair arranged in linein the coolant flow direction D (aligned in the vertical direction inFIG. 1). Accordingly, each of the pair of the substrates 3A and 3B arearranged on the upstream side and the downstream side as a pair in thecooling structure as well. Note that the concept of the lower arm andthe upper arm will be described later according to FIG. 6. In thedescription below, the lower arm substrate 3A and the upper armsubstrate 3B are generically referred to simply as “substrate 3,” andthe lower arm switching element 4A and the upper arm switching element4B are generically referred to simply as “switching element 4.”

Each substrate 3 includes one each of the switching element 4, the diodeelement 5, and the connection terminal area 6. Specifically, in thesubstrate 3, a copper foil 10 is provided on both the upper and lowersurfaces of a substrate body 21 formed of an insulating substrate. Thecopper foil 10 on the lower side is secured to a base plate 2 by asolder (not shown), and the copper foil 10 on the upper side securesthereon the switching element 4 and the diode element 5 via a solder(not shown). The switching element 4 is specifically an insulated gatebipolar transistor (IGBT) element, and the diode element 5 isspecifically a free wheel diode (FWD) element. Therefore, the switchingelement 4 has the highest heating value in the substrate 3. Theconnection terminal area 6 is provided to be placed directly on thesubstrate body 21 in a region in which the upper side copper foil 10 isnot provided. Although omitted in FIG. 1, a lead pin 22 (see FIG. 7 andFIG. 8) for electrically connecting the switching element 4 and thecontrol substrate 9 is secured to the connection terminal area 6 via asolder. In the connection terminal area 6, a wire bonding forelectrically connecting the switching element 4 and the lead pin 22 isalso performed.

The arrangement of the switching element 4, the diode element 5, and theconnection terminal area 6 on each substrate 3 is as follows. That is,as shown in FIG. 1, the switching element 4 and the diode element 5 arearranged in line in the perpendicular direction C (horizontal directionin FIG. 1). In the example shown in the drawing, the switching element 4has an external shape slightly larger than that of the diode element 5.The central position of the diode element 5 in the coolant flowdirection D is arranged in a position deflected to one side of thecoolant flow direction D (side apart from the connection terminal area6) with respect to the central position of the switching element 4 inthe coolant flow direction D, whereby the edges of the switching element4 and the diode element 5 on one side in the coolant flow direction Dare in a single straight line. In the example shown in FIG. 1, “one sidein the coolant flow direction D” refers to the downstream side of thecoolant flow direction D (upper side in FIG. 1) for the lower armsubstrate 3A, and to the upstream side of the coolant flow direction D(lower side in FIG. 1) for the upper arm substrate 3B. The switchingelement 4 and the connection terminal area 6 are arranged to differ inpositions in the coolant flow direction D. Specifically, the connectionterminal area 6 is arranged on the other side (side that is between thelower arm substrate 3A and the upper arm substrate 3B) in the coolantflow direction D in a position approximately the same as that of theswitching element 4 in the perpendicular direction C and adjacent to theswitching element 4. In the example shown in FIG. 1, “the other side inthe coolant flow direction D” refers to the upstream side of the coolantflow direction D (lower side in FIG. 1) for the lower arm substrate 3A,and to the downstream side of the coolant flow direction D (upper sidein FIG. 1) for the upper arm substrate 3B. In the example shown in thedrawing, the substrate body 21 of each substrate 3 is formed in a plateshape having a long rectangular planar shape in the perpendiculardirection C in accordance with the arrangement of each element and thelike.

As described above, in the relation between the pair of the lower armsubstrate 3A and the upper arm substrate 3B arranged in line in thecoolant flow direction D (in line in the vertical direction in FIG. 1),i.e., the relation between the pair of substrates 3 forming each set,the switching element 4 is arranged on one side in the perpendiculardirection C in one substrate 3, and the diode element 5 is arranged onthe one side in the perpendicular direction C in the other substrate 3.Specifically, in the lower arm substrate 3A, the switching element 4 isarranged on the left side (first side) in the perpendicular direction C(left side in FIG. 1), and the diode element 5 is arranged on the rightside (second side) in the perpendicular direction C (right side in FIG.1). On the other hand, in a manner opposite to that of the lower armsubstrate 3A, in the upper arm substrate 3B, the diode element 5 isarranged on the left side in the perpendicular direction C, and theswitching element 4 is arranged on the right side in the perpendiculardirection C. In this embodiment, in order to achieve an arrangement ofthe pair of the lower arm substrate 3A and the upper arm substrate 3Bthat satisfies the relation, the pair of substrates 3A and 3B hasidentical configurations, and the pair of substrates 3A and 3B arearranged to be point symmetrical. In this case, the pair of substrates3A and 3B are arranged to be point symmetrical with respect to thecentral position in both the coolant flow direction D and theperpendicular direction C of the pair of substrates 3A and 3B as thereference.

The pair of substrates 3A and 3B arranged in line in the coolant flowdirection D has an arrangement configuration such as that describedabove, whereby the lower arm switching element 4A and the upper armswitching element 4B of the pair of substrates 3A and 3B are arranged tobe deflected to differ in positions in the perpendicular direction C.Therefore, regarding each of the plurality of parallel flows flowingthrough the plurality of coolant flow paths 7 formed between the fins 8,a single flow of the coolant flowing through one coolant flow path 7 maybasically cool only one of the upper arm switching element 4B and thelower arm switching element 4A. Therefore, both of the switchingelements 4A and 4B of the pair of substrates 3A and 3B can beappropriately cooled. That is, it can suppress a decrease in the coolingperformance for the lower arm switching element 4A on the downstreamside, due to a configuration in which a single flow of the coolanthaving a higher temperature after cooling the upper arm switchingelement 4B on the upstream side in the coolant flow direction D furthercools the lower arm switching element 4A on the downstream side.

In this embodiment, both of the connection terminal area 6 of the pairof substrates 3A and 3B are arranged on the other substrate 3 side withrespect to the switching element 4 of each substrate 3. Specifically, inthe lower arm substrate 3A, the connection terminal area 6 is arrangedon the upper arm substrate 3B side with respect to the lower armswitching element 4A. In the upper arm substrate 3B, the connectionterminal area 6 is arranged on the lower arm substrate 3A side withrespect to the upper arm switching element 4B. Thereby, the lower armswitching element 4A and the upper arm switching element 4B are arrangedwith both of the connection terminal areas 6 of the pair of substrates3A and 3B there between in the coolant flow direction D, whereby theswitching elements 4A and 4B which generate most of the heat, arearranged in positions apart from each other in the pair of substrates 3Aand 3B. Thus, a thermal interference on the base plate 2 caused by heattransmitted from each of the switching elements 4A and 4B of the pair ofsubstrates 3A and 3B can be suppressed.

Note that, in this embodiment, as described above, the connectionterminal area 6 is arranged in a position approximately the same as thatof the switching element 4 in the perpendicular direction C, whereby theconnection terminal area 6 of each of the pair of substrates 3A and 3Bis arranged on one side in the perpendicular direction C in onesubstrate 3 and is arranged on the other side in the perpendiculardirection C in the other substrate 3, in a manner similar to theswitching element 4 of each of the pair of substrates 3A and 3B.Specifically, the connection terminal area 6 is arranged on the leftside in the perpendicular direction C (left side in FIG. 1) in the lowerarm substrate 3A, and is arranged on the right side in the perpendiculardirection C (right side in FIG. 1) in the upper arm substrate 3B. Withthe connection terminal area 6 arranged in this manner, the connectionterminal area 6 of the lower arm substrate 3A and the connectionterminal area 6 of the upper arm substrate 3B can be aligned alternatelyalong the perpendicular direction C. Thus, as shown in FIG. 7, theplurality of lead pins 22 secured to the connection terminal area 6 ofeach substrate 3 is easily arranged in one line in the perpendiculardirection C. Thus, the wiring pattern of the control substrate 9described later can be simplified, and a soldering step of the lead pin22 and the control substrate 9 can be simplified.

1-3. Configuration of Inverter Circuit

Next, the electrical configuration of the inverter circuit 11 formed ofthe semiconductor module 1 according to this embodiment will bedescribed. As shown in FIG. 6, the inverter circuit 11 is a circuit fordriving the three-phase AC electric motor 31. That is, the invertercircuit 11 includes a U-phase arm 32 u, a V-phase arm 32 v, and aW-phase arm 32 w respectively provided corresponding to a U-phase coil31 u, a V-phase coil 31 v, and a W-phase coil 31 w (corresponding toeach phase of a U-phase, a V-phase, and a W-phase) of the three-phase ACelectric motor 31. The arms 32 u, 32 v, and 32 w for each phase eachhave a pair of the lower arm 33 and the upper arm 34 capable ofoperating in a complementary manner. The lower arm 33 has the lower armswitching element 4A formed of the IGBT element, and the diode element 5connected in parallel between an emitter and a collector of the lowerarm switching element 4A. Similarly, the upper arm 34 has the upper armswitching element 4B formed of the IGBT element, and the diode element 5connected in parallel between an emitter and a collector of the upperarm switching element 4B. In the diode element 5, an anode is connectedto the emitter of the switching elements 4A and 4B, and a cathode isconnected to the collector of the switching elements 4A and 4B.

The pair of lower arm 33 and the upper arm 34 for each phase areconnected in line such that the lower arm 33 is on the side of thenegative electrode N which is the ground, and the upper arm 34 is on theside of the positive electrode P which is the source voltage.Specifically, the emitter of the lower arm switching element 4A isconnected to the negative electrode N, and the collector of the upperarm switching element 4B is connected to the positive electrode P. Thatis, the lower arm switching element 4A is the lower side switch, and theupper arm switching element 4B is the high side switch. The collector ofthe lower arm switching element 4A and the emitter of the upper armswitching element 4B are connected to each of the U-phase coil 31 u, theV-phase coil 31 v, and the W-phase coil 31 w of the electric motor 31corresponding to each of the arms 32 u, 32 v, and 32 w.

In the relation with each substrate 3 of the semiconductor module 1, thelower arm switching element 4A and the diode element 5 of the lower armsubstrate 3A form the lower arm 33, and the upper arm switching element4B and the diode element 5 of the upper arm substrate 3B form the upperarm 34 of the inverter circuit 11. That is, of six substrates 3 arrangedon the base plate 2, the three lower arm substrates 3A arranged on thedownstream side in the coolant flow direction D (upper side in FIG. 1)each form the lower arm 33 of the U-phase arm 32 u, the V-phase arm 32v, and the W-phase arm 32 w, and the three upper arm substrates 3Barranged on the upstream side in the coolant flow direction D (lowerside in FIG. 1) each form the upper arm 34 of the U-phase arm 32 u, theV-phase arm 32 v, and the W-phase arm 32 w. On the base plate 2, thepair of (the set of) the lower arm substrate 3A and the upper armsubstrate 3B arranged in line in the coolant flow direction D (in linein the vertical direction in FIG. 1) each form one of the U-phase arm 32u, the V-phase arm 32 v, and the W-phase arm 32 w. Thus, for example,the pair of substrates 3A and 3B on the left side in the perpendiculardirection C (left side in FIG. 1) form the U-phase arm 32 u, the pair ofsubstrates 3A and 3B in the center in the perpendicular direction C formthe V-phase arm 32 v, and the pair of substrates 3A and 3B on the rightside in the perpendicular direction C (right side in FIG. 1) form theW-phase arm 32 w.

1-4. Upper Section Configuration of Semiconductor Module

Next, the upper section configuration provided above the base plate 2 inthe semiconductor module 1 will be described. As shown in FIG. 7 andFIG. 8, the semiconductor module 1 has a resin case 41 placed on thebase plate 2 and provided to surround six substrates 3 described above,and the control substrate 9 is supported above the six substrates 3 bythe case 41 as the upper section configuration.

The case 41 externally has a rectangular parallelepiped form in whichthe planar shape is a rectangular shape slightly larger than that of thebase plate 2. The case 41 forms a storage space 42 which stores sixsubstrates 3 placed on the base plate 2 and has a circumference wallsection 41 a provided to surround the circumference of the storage space42. Note that, a filler such as an epoxy resin fills the storage space42 and is hardened in the storage space 42. Therefore, six substrates 3placed on the base plate 2 and the case 41 are eventually integrated. Asshown in FIG. 7, a tight hole 43, into which tightening unit such as abolt for fastening the case 41 on the base plate 2 is inserted, isprovided to the four corners of the case 41.

The upper surface of the circumference wall section 41 a is formed oftwo surfaces, a first upper surface 41 c and a second upper surface 41d, having different heights. The first upper surface 41 c is a longrectangular surface in the perpendicular direction C provided to each ofthe upstream side and the downstream side of the coolant flow directionD (upper side and the lower side in FIG. 7). The second upper surface 41d is a surface one step lower than the first upper surface 41 c. Thefirst upper surface 41 c of the case 41 is provided with a positiveterminal 44 a, a negative terminal 44 b, and an output terminal 44 c asexternal lead-out terminals of a lead frame (not shown) disposed in thecase 41 to be electrically connected to each substrate 3. One each ofthe positive terminal 44 a and the negative terminal 44 b are providedto the first upper surface 41 c on the lower side in FIG. 7, and threeoutput terminals 44 c are provided to the first upper surface 41 c onthe upper side in FIG. 7. The positive terminal 44 a is electricallyconnected to the positive electrode P, and the negative terminal 44 b iselectrically connected to the negative electrode N (see FIG. 6). Thethree output terminals 44 c are each electrically connected to theU-phase coil 31 u, the V-phase coil 31 v, and the W-phase coil 31 w (seeFIG. 6) of the three-phase AC electric motor 31.

The control substrate 9 is arranged above the second upper surface 41 dof the case 41. Therefore, internal thread portion (not shown) to whicha bolt 45 for fastening the control substrate 9 is screwed is formed ina plurality of positions near the edges on both sides in theperpendicular direction C of the second upper surface 41 d. The controlsubstrate 9 is tightened and secured to the case 41 by the plurality ofbolts 45. The control substrate 9 is arranged to be parallel with thesurfaces with a certain interval by a spacer 46 arranged between thecontrol substrate 9 and the upper surface of the second upper surface 41d.

The plurality of lead pins 22 secured to the connection terminal area 6of each substrate 3 penetrates the control substrate 9, and is solderedand fastened to the wiring pattern (not shown) provided on the uppersurface of the control substrate 9. In this embodiment, the lead pins 22of each of six substrates 3 are arranged in one line in theperpendicular direction C. With the arrangement in which the lead pins22 are aligned in one line on the control substrate 9, the wiringpattern of the control substrate 9 can be simplified, and the solderingstep of the lead pin 22 and the control substrate 9 can be simplified.The control substrate 9 is a substrate in which a control circuit fordriving the inverter circuit 11 is formed, and is formed of a printsubstrate mounted with a specific circuit part. The lead pin 22electrically connects the control substrate 9 and the plurality ofsubstrates 3 arranged on the base plate 2.

Further, on the control substrate 9, a temperature detection circuit 9 afunctioning as a temperature detection unit that detects the temperatureof the switching element 4 of each substrate 3 is mounted. Thetemperature detection circuit 9 a is an arithmetic circuit that detectsthe temperature of each switching element 4 by detecting the voltagebetween the anode and the cathode of a temperature detection diode (notshown) provided to the switching element 4 and performing a specificarithmetic operation. In this embodiment, only the lower arm switchingelement 4A of the lower arm substrate 3A, arranged on the downstreamside of the coolant flow direction D, of the switching elements 4A and4B of each of the pair of substrates 3A and 3B is provided with thetemperature detection circuit 9 a. That is, the temperature detectioncircuit 9 a is omitted in the upper arm switching element 4B of theupper arm substrate 3B arranged on the upstream side of the coolant flowdirection D. Thus, in the semiconductor module 1, wherein thetemperature detection circuit 9 a provided to the lower arm switchingelement 4A arranged on the downstream side of the coolant flow directionD performs the temperature detection for a temperature management ofboth of the switching elements 4A and 4B of the pair of substrates 3Aand 3B. Note that, the control substrate 9 monitors the temperature ofthe switching elements 4A and 4B to be kept within a specific operationsecurity temperature range, and performs control to stop the operationand the like of the switching elements 4A and 4B when the temperatureexceeds the temperature range, for example as the temperature managementof the switching elements 4A and 4B.

The temperature detection circuit 9 a is provided only to the lower armswitching element 4A arranged on the downstream side of the coolant flowdirection D in this manner, whereby the number of the temperaturedetection circuits 9 a can be reduced by half of that of a case wherethe temperature detection circuit 9 a is provided to the upper armswitching element 4B as well. Normally, the temperature of the coolantis higher on the downstream side than on the upstream side of thecoolant flow direction D, whereby the lower arm switching element 4Aarranged on the downstream side is likely to have a higher temperaturethan that of the upper arm switching element 4B arranged on the upstreamside. Therefore, even if the temperature management is performed usingonly the temperature detection result of the lower arm switching element4A, the temperature of the upper arm switching element 4B does notexceed the specific operation security temperature range and therebydoes not cause a problem. Further, in this embodiment, since only thelower arm switching element 4A is arranged on the downstream side of thecoolant flow direction D, the configuration of the temperature detectioncircuit 9 a can be simplified. That is, all temperature detectioncircuits 9 a are used for the temperature detection of the lower armswitching element 4A, whereby each temperature detection circuit 9 a canbe an arithmetic circuit in which the electric potential of the negativeelectrode N (ground) is the reference. Therefore, the configuration ofthe temperature detection circuit 9 a can be simplified compared to thetemperature detection circuit 9 a in which the electric potential of thepositive electrode P is the reference. Thus, the cost of thesemiconductor module 1 can be reduced.

2. Second Embodiment

A second embodiment of the present invention will be described accordingto the drawing. FIG. 9 is a plan view showing the configuration of themain section of the semiconductor module 1 according to this embodiment.As shown in the drawing, the semiconductor module 1 according to thisembodiment is formed of only one set of the pair of the lower armsubstrate 3A and the upper arm substrate 3B placed on one base plate 2.That is, the number of the substrates 3 placed on one base plate 2 inthe semiconductor module 1 according to this embodiment differs fromthat of the first embodiment. Note that the configuration is similar tothat of the first embodiment, unless otherwise mentioned in thisembodiment.

Therefore, in the semiconductor module 1 according to this embodiment,the width of the base plate 2 in the perpendicular direction C isnarrower, and the full width W of the coolant flow path 7 is narrowercompared to the semiconductor module 1 according to the firstembodiment. Although omitted in the drawing, the shape of the case 41matches the shape of the base plate 2, and the control substrate 9 isformed to be suitable for controlling the pair of substrates 3A and 3Bin the upper section configuration of the semiconductor module 1. Threesemiconductor modules 1 can be used in combination to form the invertercircuit 11 similar to that of the first embodiment. When thesemiconductor module 1 is used alone, a chopper circuit can be formed bya combination with a coil, a capacitor, and the like, for example.Although omitted in the drawing, forming the semiconductor module 1 withtwo sets or four or more sets of the pair of the lower arm substrate 3Aand the upper arm substrate 3B placed on one base plate 2 is also onepreferred embodiment of the present invention. For example, in the caseof forming a single-phase AC inverter circuit and the like, it ispreferable to place two sets of the pair of lower arm substrate 3A andthe upper arm substrate 3B on one base plate 2.

3. Third Embodiment

A third embodiment of the present invention will be described accordingto the drawing. FIG. 10 is a plan view showing the configuration of themain section of the semiconductor module 1 according to this embodiment.In the semiconductor module 1 according to this embodiment, thearrangement configuration of the substrate 3 differs from that of thefirst and second embodiments. In order to simplify the drawing and thelike, an example of a configuration in which only one set of the pair ofsubstrates 3A and 3B is placed on one base plate 2, as in the secondembodiment, will be described. However, a configuration in which aplurality of the sets of the pair of the substrates 3A and 3B are placedon the base plate 2, as in the first embodiment, may obviously beapplied in a similar manner. Note that the configuration is similar tothat of the first embodiment or the second embodiment, unless otherwisementioned in this embodiment.

In the semiconductor module 1 according to this embodiment, thearrangement of the switching element 4, the diode element 5, and theconnection terminal area 6 in the upper arm substrate 3B is the same asthat of the first and second embodiments, but the arrangement of theswitching element 4, the diode element 5, and the connection terminalarea 6 in the lower arm substrate 3A is different. That is, in the lowerarm substrate 3A, the switching element 4 is arranged on the upper armsubstrate 3B side with respect to the connection terminal area 6 in thisembodiment. Therefore, in the semiconductor module 1, only theconnection terminal area 6 of the upper arm substrate 3B, which is oneof the pair of substrates 3A and 3B, is arranged on the lower armsubstrate 3A side with respect to the switching element 4B of thesubstrate 3B. Note that, since the diode element 5 of the lower armsubstrate 3A is arranged in line with the switching element 4 in theperpendicular direction C, the diode element 5 is arranged on the upperarm substrate 3B side with respect to the connection terminal area 6 ina manner similar to the switching element 4. The positional relationbetween the switching element 4 and the diode element 5 in theperpendicular direction C in each of the substrates 3A and 3B is similarto that of the first and second embodiments.

Therefore, in the semiconductor module 1, the lower arm substrate 3A andthe upper arm substrate 3B do not have the same configuration. The lowerarm substrate 3A has a configuration in which the positional relation ofthe upper arm substrate 3B is reversed in the perpendicular direction Cas in a mirror. The arrangement configuration of the substrate 3 of thesemiconductor module 1 according to this embodiment is achieved byarranging the lower arm substrate 3A and the upper arm substrate 3B inline such that the switching elements 4 are both positioned on theupstream side of the coolant flow direction D.

4. Fourth Embodiment

A fourth embodiment of the present invention will be described accordingto the drawing. FIG. 11 is a plan view showing the configuration of themain section of the semiconductor module 1 according to this embodiment.In the semiconductor module 1 according to this embodiment, thearrangement configuration of the substrate 3 differs from that of thefirst to third embodiments. In order to simplify the drawing and thelike, an example of a configuration in which only one set of the pair ofsubstrates 3A and 3B is placed on one base plate 2, as in the secondembodiment, will be described. However, a configuration in which aplurality of the sets of the pair of the substrates 3A and 3B are placedon the base plate 2, as in the first embodiment, may obviously beapplied in a similar manner. Note that the configuration is similar tothat of the first embodiment or the second embodiment, unless otherwisementioned in this embodiment.

In the semiconductor module 1 according to this embodiment, thearrangement of the switching element 4, the diode element 5, and theconnection terminal area 6 in the lower arm substrate 3A is the same asthat of the first and second embodiments, but the arrangement of theswitching element 4, the diode element 5, and the connection terminalarea 6 in the upper arm substrate 3B is different. That is, in the upperarm substrate 3B, the switching element 4 is arranged on the lower armsubstrate 3A side with respect to the connection terminal area 6 in thisembodiment. Therefore, in the semiconductor module 1, only theconnection terminal area 6 of the lower arm substrate 3A, which is oneof the pair of substrates 3A and 3B, is arranged on the upper armsubstrate 3B side with respect to the switching element 4A of thesubstrate 3A. Note that, since the diode element 5 of the upper armsubstrate 3B is arranged in line with the switching element 4 in theperpendicular direction C, the diode element 5 is arranged on the lowerarm substrate 3A side with respect to the connection terminal area 6 ina manner similar to the switching element 4. The positional relationbetween the switching element 4 and the diode element 5 in theperpendicular direction C in each of the substrates 3A and 3B is similarto that of the first and second embodiments.

Therefore, in the semiconductor module 1, the lower arm substrate 3A andthe upper arm substrate 3B do not have the same configuration. The upperarm substrate 3B has a configuration in which the positional relation ofthe lower arm substrate 3A is reversed in the perpendicular direction Cas in a mirror. The arrangement configuration of the substrate 3 of thesemiconductor module 1 according to this embodiment is achieved byarranging the lower arm substrate 3A and the upper arm substrate 3B inline such that the switching elements 4 are both positioned on thedownstream side of the coolant flow direction D.

5. Fifth Embodiment

A fifth embodiment of the present invention will be described accordingto the drawing. FIG. 12 is a plan view showing the configuration of themain section of the semiconductor module 1 according to this embodiment.The semiconductor module 1 according to this embodiment differs fromthat of the first to fourth embodiments mainly in that each substrate 3includes two each of the switching element 4, the diode element 5, andthe connection terminal area 6. In order to simplify the drawing and thelike, an example of a configuration in which only one set of the pair ofsubstrates 3A and 3B is placed on one base plate 2, as in the secondembodiment, will be described. However, a configuration in which aplurality of the sets of the pair of the substrates 3A and 3B are placedon the base plate 2, as in the first embodiment, may obviously beapplied in a similar manner. Note that the configuration is similar tothat of the first embodiment or the second embodiment, unless otherwisementioned in this embodiment.

In the semiconductor module 1 according to this embodiment, thearrangement of the switching element 4, the diode element 5, and theconnection terminal area 6 on each substrate 3 is as follows. That is,the two switching elements 4 are adjacently arranged in line with eachother in the coolant flow direction D. Also, the two diode elements 5are adjacently arranged in line with each other in the coolant flowdirection D. The two switching elements 4 and the two diode elements 5are arranged in line in the perpendicular direction C. The two switchingelements 4 and the two diode elements 5 are arranged on the same copperfoil 10. In the example shown in the drawing, the switching element 4has an external shape slightly larger than that of the diode element 5.The central position of the diode element 5 in the coolant flowdirection D is arranged in a position deflected to one side in which thetwo diode elements 5 face each other with respect to the centralposition of the switching element 4 in the coolant flow direction D,whereby the edges on the facing side of the two switching elements 4 andthe two diode elements 5 are in single straight lines. The connectionterminal areas 6 are arranged in a position approximately the same asthat of the two switching elements 4 in the perpendicular direction C,and are respectively arranged adjacent to both sides (upstream side anddownstream side) of the coolant flow direction D with the two switchingelements 4 there between.

In the relation between the pair of the lower arm substrate 3A and theupper arm substrate 3B arranged in line in the coolant flow direction D(in line in the vertical direction in FIG. 12), the two switchingelements 4 are arranged on one side in the perpendicular direction C inone substrate 3, and the two diode elements 5 are arranged on the oneside in the perpendicular direction C in the other substrate 3.Specifically, in the lower arm substrate 3A, the two switching elements4 are arranged on the left side in the perpendicular direction C (leftside in FIG. 12), and the two diode elements 5 are arranged on the rightside in the perpendicular direction C (right side in FIG. 12). On theother hand, in the upper arm substrate 3B, in a manner opposite to thatof the lower arm substrate 3A, the two diode elements 5 are arranged onthe left side in the perpendicular direction C, and the two switchingelements 4 are arranged on the right side in the perpendicular directionC. Note that the connection terminal area 6 is arranged, in a mannersimilar to the switching element 4, on the left side in theperpendicular direction C (left side in FIG. 12) in the lower armsubstrate 3A, and is arranged on the right side in the perpendiculardirection C in the upper arm substrate 3B. In this embodiment, in orderto achieve an arrangement of the pair of the lower arm substrate 3A andthe upper arm substrate 3B that satisfies such a relation, the pair ofsubstrates 3A and 3B has the same configuration, and the pair ofsubstrates 3A and 3B are arranged to be point symmetrical. In this case,the pair of substrates 3A and 3B are arranged to be point symmetricalwith respect to the central position in both the coolant flow directionD and the perpendicular direction C of the pair of substrates 3A and 3Bas the reference.

6. Other Embodiments

(1) When a plurality of semiconductor modules 1 described above in eachembodiment are used in combination and each semiconductor module 1 has adifferent heating value, it is preferable to arrange the semiconductormodules 1 in order so that the semiconductor module 1 having a higherheating value is on the upstream side of the coolant flow direction D.FIG. 13 shows an example in which two semiconductor modules 1A and 1Bhaving different heating values are arranged in line in the coolant flowdirection D. In this example, the configuration of each semiconductormodule 1 is the same as that according to the first embodiment. Thefirst semiconductor module 1A arranged on the upstream side of thecoolant flow direction D has a higher heating value than the secondsemiconductor module 1B arranged on the downstream side of the coolantflow direction D. In this example, the coolant passes through thecoolant flow path 7 of the first semiconductor module 1A and then passesthrough the coolant flow path 7 of the second semiconductor module 1Baccording to the flow direction D. This configuration allows thedecrease in cooling performance, due to the coolant gradually rising intemperature as the coolant flows downstream in the flow direction D, andthe heating value of each semiconductor module 1 to be balanced. Notethat, when the plurality of semiconductor modules 1 have differentheating values in this manner, the inverter circuit 11 formed of eachsemiconductor module 1 is formed to drive each electric motor havingdifferent outputs, for example, whereby the amount of current flowingthrough the switching element 4 of each semiconductor module 1 maydiffer.

(2) When a plurality of the semiconductor modules 1 in each embodimentdescribed above are used in combination, it is preferable to arrange twosemiconductor modules 1 such that the positive terminal 44 a and thenegative terminal 44 b of each semiconductor module 1 are positioned ona side close to the other adjacent semiconductor module 1. FIG. 14 showsan example of such an arrangement of the two semiconductor modules 1Aand 1B. In this example, the configuration of each semiconductor module1 is the same as that of the first embodiment. The first semiconductormodule 1A arranged on the lower side in FIG. 14 is arranged in adirection in which the positions of the positive terminal 44 a and thenegative terminal 44 b are on the side of the adjacent secondsemiconductor module 1B. The second semiconductor module 1B arranged onthe upper side in FIG. 14 is arranged in a direction in which thepositions of the positive terminal 44 a and the negative terminal 44 bare on the side of the adjacent first semiconductor module 1A. Byarranging the two semiconductor modules 1A and 1B in this manner, apositive bus bar 48A and a negative bus bar 48B of the two semiconductormodules 1A and 1B can be used commonly, and further, the positive busbar 48A and the negative bus bar 48B can be arranged in parallel, asshown in FIG. 14. By arranging the positive bus bar 48A and the negativebus bar 48B in parallel in this manner, the occurrence of a magneticfield around the positive bus bar 48A and the negative bus bar 48B canbe cancelled out by the influence of parallel currents each flowing inopposite directions in the positive bus bar 48A and the negative bus bar48B, whereby the inductance of the positive bus bar 48A and the negativebus bar 48B can be reduced.

(3) In each embodiment described above, a case where a cooling liquid,in which ethylene glycol and the like are added to water, is used as thecoolant have been described as an example, but the coolant of thepresent invention is not limited thereto. That is, various cooling mediaof a known liquid or gas may suitably be used for the semiconductormodule 1 according to the present invention.

(4) In each embodiment described above, as a specific example of theconfiguration in which the elements or substrates are “arranged in linein the coolant flow direction D,” the configuration in which thedirection connecting the central positions of a plurality of elements orsubstrates is approximately parallel with respect to the coolant flowdirection D has been described. However, the scope of the configurationin which the elements or substrates are “arranged in line in the coolantflow direction D” is not limited thereto. That is, even if the directionconnecting the central positions of the plurality of elements orsubstrates is arranged in a direction which intersect the coolant flowdirection D, it may be considered a configuration in which the elementsor substrates are “arranged in line in the coolant flow direction D” asone preferred embodiment of the present invention in the case where atleast a part of the elements or substrates are in a positional relationoverlapping with each other in the perpendicular direction C.

(5) Similarly, in each embodiment described above, the configuration inwhich the direction connecting the central positions of a plurality ofelements or substrates is arranged approximately parallel with respectto the perpendicular direction C has been described as a specificexample of the configuration in which the elements or substrates are“arranged in line in the perpendicular direction C with respect to thecoolant flow direction D.” However, the scope of the configuration inwhich the elements or substrates are “arranged in line in theperpendicular direction C” is not limited thereto. That is, even if thedirection connecting the central positions of the plurality of elementsor substrates is arranged in a direction which intersect theperpendicular direction C, it may be considered a configuration in whichthe elements or substrates are “arranged in line in the perpendiculardirection C” as one preferred embodiment of the present invention in thecase where at least a part of the elements or substrates are in apositional relation overlapping with each other in coolant flowdirection D.

(6) In each embodiment described above, an example in which theplurality of parallel fins 8 is provided to the lower surface 2B of thebase plate 2 as a parallel flow formation unit has been described.However, the specific configuration of the parallel flow formation unitis not limited thereto. Thus, for example, a configuration in which theplurality of parallel fins 8 are formed on the side of the water pathformation member 12 having a body separate from the base plate 2 and inwhich the upper surface of each fin 8 contacts the base plate 2 is alsoone preferred embodiment of the present invention. Any number, interval,and the like of the fins 8 may also be used. The parallel flow formationunit may also be formed by a component other than the fin 8. Forexample, parallel flows of the coolant in a specific direction can beformed in a similar manner by a plurality of long penetration holes,grooves, or the like provided to the base plate 2. In that case, thepenetration hole, groove, or the like is the parallel flow formationunit.

(7) A configuration in which the tip of the fin 8 has a specific gapwith respect to the facing plate member is also suitable. That is,although the case where the bottom surface (lower surface in FIG. 2 andFIG. 3) of the fin 8 as the parallel flow formation unit is provided tocontact the contact plate section 12 b of the water path formationmember 12 has been described as an example in each embodiment describedabove, a configuration in which the bottom surface of the fin 8 has aspecific gap with respect to the contact plate section 12 b is alsosuitable. Similarly, when the fin 8 is formed on the water pathformation member 12 side, a configuration in which the upper surface ofthe fin 8 has a specific gap with respect to the lower surface 2B of thebase plate 2 is also suitable.

(8) In each embodiment described above, an example in which each of theparallel flows of the coolant formed by the parallel flow formation unitis linear has been described. However, the parallel flows of the coolantformed by the parallel flow formation unit is not limited to a linearflow, and may be a curved flow having a bend section such as a wave formas one preferred embodiment of the present invention. In this case, ifthe parallel flow formation unit is the fin 8, for example, each fin 8is curved in a bended wave form or the like in planar view.

(9) In each embodiment described above, an example in which the lowerarm substrate 3A including the lower arm switching element 4A isarranged on the downstream side in the coolant flow direction D withrespect to the upper arm substrate 3B has been described. However, aconfiguration in which the lower arm substrate 3A is arranged on theupstream side in the coolant flow direction D with respect to the upperarm substrate 3B is also one preferred embodiment of the presentinvention. In this case, in terms of reliability of the temperaturemanagement, it is preferable to omit the temperature detection circuit 9a for the lower arm switching element 4A and provide the temperaturedetection circuit 9 a of the upper arm switching element 4B arranged onthe downstream side of the coolant flow direction D. Note that this doesnot preclude a configuration in which the temperature detection circuit9 a of the upper arm switching element 4B arranged on the downstreamside of the coolant flow direction D is omitted and the temperaturedetection circuit 9 a of the lower arm switching element 4A arranged onthe upstream side of the coolant flow direction D is provided. Thetemperature detection circuit 9 a may also be provided to both of thelower arm switching element 4A and the upper arm switching element 4B.

(10) In each embodiment described above, a configuration in which theplurality of substrates 3 are arranged on the upper surface 2A of thebase plate 2 and the coolant flow path 7 is provided to the lowersurface 2B of the base plate 2 has been described as an example, but theembodiment of the present invention is not limited thereto. That is, thearrangement direction of the base plate 2 is arbitrary, and setting thesurface in which the plurality of substrates 3 are arranged to facedownward or sideways is also one preferred embodiment of the presentinvention.

(11) In the first, second, and fifth embodiments described above, anexample in which the pair of substrates 3A and 3B have the exact sameconfiguration have been described. However, in order to achieve thearrangement of the pair of substrates 3A and 3B described above, it isnot necessary that the configurations of the pair of substrates 3A and3B be completely the same, as long as at least the arrangements of theswitching element 4, the diode element 5, and the connection terminalarea 6 of each substrate 3 are the same. Therefore, a configuration inwhich the lower arm substrate 3A and the upper arm substrate 3B have thesame arrangements regarding the switching element 4, the diode element5, and the connection terminal area 6 but have different configurationsotherwise, and in which the pair of substrates 3A and 3B are arranged tobe point symmetrical is also one preferred embodiment of the presentinvention.

(12) In each embodiment described above, an example in which thesemiconductor module 1 is applied to the inverter circuit 11 or thechopper circuit has mainly been described. However, the scope ofapplication of the present invention is not limited thereto, and may besuitably utilized for various semiconductor modules 1 that requireappropriate cooling of the switching element 4.

The present invention can be suitably utilized for a semiconductormodule including a base plate, a plurality of substrates placed on onesurface of the base plate and each including a switching element, adiode element, and a connection terminal area, and a coolant flow pathprovided to contact the other surface of the base plate.

According to an exemplary aspect of the invention, the switchingelements of each of the pair of substrates arranged in series in thecoolant flow direction are arranged in positions apparently differentfrom each other in the perpendicular direction with respect to thecoolant flow direction, in a configuration in which the switchingelement and the diode element of each of the plurality of substratesplaced on the first surface of the base plate are arranged in series andin line in the perpendicular direction with respect to the coolant flowdirection in the coolant flow path provided to the second surface of thebase plate. Thus, a single flow of the coolant along the parallel flowsin the coolant flow path can basically cool only the switching elementof one of the pair of substrates. Therefore, each switching element ofboth of the pair of substrates can appropriately be cooled. In otherwords, the decrease in cooling performance for the switching element onthe downstream side, due to a configuration in which a single flow ofthe coolant having a higher temperature after cooling the switchingelement of one substrate on the upstream side in the coolant flowdirection further cools the switching element of the other substrate onthe downstream side, can be suppressed. Thus, the switching element ofall substrates placed on the first surface of the base plate canappropriately be cooled.

With this configuration, the connection terminal area of at least onesubstrate of the pair of substrates each including one of the pair ofthe lower arm switching element and the upper arm switching element isarranged on a side of the other substrate with respect to the switchingelement of the substrate, whereby the switching elements of both of thepair of substrates are arranged in the coolant flow direction with theconnection terminal area of at least one substrate there between.Therefore, the switching elements, which generate most of the heat, ofeach substrate are arranged in positions relatively apart from eachother. Thus, a thermal interference on the base plate caused by heat ofthe switching element included in each of the pair of substrates can besuppressed to appropriately cool the switching element of allsubstrates.

According to an exemplary aspect of the invention, as described above,the switching elements of each of the pair of substrates arranged inseries in the coolant flow direction are arranged in positionsapparently different from each other in the perpendicular direction withrespect to the coolant flow direction, and the pair of substrates can beused commonly. Therefore, since the switching elements of each of thepair of substrates arranged in series in the coolant flow direction arearranged in positions apparently different from each other in theperpendicular direction with respect to the coolant flow direction, aplurality of types of substrates having different arrangements of theelements and the like are not necessary, whereby an increase in themanufacturing cost of the semiconductor module can be suppressed.

According to an exemplary aspect of the invention, the two switchingelements of each of the pair of substrates are arranged in the coolantflow direction with the connection terminal areas of both substratesthere between. Accordingly, the switching elements which generate mostof the heat are arranged in positions apart from each other in the pairof substrates, whereby the occurrence of a thermal interference on thebase plate caused by heat transmitted from each switching element of thepair of substrates can be suppressed. Thus, the switching element of allsubstrates can appropriately be cooled.

According to an exemplary aspect of the invention, the parallel flows ofthe coolant in a direction along the plurality of fins can appropriatelybe formed in the coolant flow path. Since providing the plurality offins can increase the surface area of the coolant flow path, the heattransmitted from the substrate to the base plate can efficiently bedischarged.

According to an exemplary aspect of the invention, the temperaturedetection unit for the switching element of the substrate arranged onthe upstream side of the coolant flow direction can be omitted.Therefore, the configuration of the temperature detection unit can besimplified, and the manufacturing cost of the semiconductor module canbe reduced. Normally, the temperature of the coolant is higher on thedownstream side than on the upstream side of the coolant flow direction,whereby the switching element of the substrate arranged on thedownstream side is likely to have a higher temperature than that of theswitching element of the substrate arranged on the upstream side.Therefore, the temperature of the switching element of the substratearranged on the upstream side does not exceed the specific operationsecurity temperature range and thereby does not cause a problem, even ifthe temperature management is performed using only the temperaturedetection result of the switching element of the substrate arranged onthe downstream side.

According to an exemplary aspect of the invention, the temperaturedetection unit can have a configuration in which the electric potentialof the ground is the reference. Therefore, the configuration can besimplified compared to the temperature detection unit in which thesource electric potential is the reference, and the manufacturing costof the semiconductor module can be reduced.

According to an exemplary aspect of the invention, all switchingelements forming the three-phase AC inverter circuit are provided to thebase plate integrally, whereby the three-phase AC inverter circuithaving a small size and light weight can easily be formed using thesemiconductor module.

1. A semiconductor module comprising: a base plate; a plurality ofsubstrates placed on one surface of the base plate, with each substrateof the plurality of substrates including a switching element, a diodeelement, and a connection terminal area; and a parallel flow formingdevice that forms parallel coolant flow paths that are provided so as tobe in contact with the other surface of the base plate, wherein: thecoolant flow paths are formed such that coolant flows in a coolant flowdirection, the switching element and the diode element are arranged inline in a perpendicular direction with respect to the coolant flowdirection, the switching element and the connection terminal area arearranged in positions differing in the coolant flow direction in each ofthe substrates, a pair of substrates of the plurality of substrates isarranged in series in the coolant flow direction, the switching elementof one of the substrates of the pair of substrates is arranged on oneside in the perpendicular direction, and the diode element of the othersubstrate of the pair of substrates is arranged on the one side in theperpendicular direction, the connection terminal area of at least onesubstrate of the pair of substrates is arranged closer to a side that isbetween the pair of substrates with respect to the switching element ofthe at least one substrate of the pair of substrates, and the switchingelements of the pair of substrates are arranged at different positionsin the perpendicular direction.
 2. The semiconductor module according toclaim 1, wherein the pair of substrates have an identical structure witheach other and are arranged to be symmetrical.
 3. The semiconductormodule according to claim 1, wherein both of the connection terminalareas of the pair of substrates are arranged closer to the side that isbetween the pair of substrates with respect to the switching elements ofeach substrate.
 4. The semiconductor module according to claim 1,wherein the parallel flow forming device is a plurality of fins arrangedparallel with each other along the other surface of the base plate. 5.The semiconductor module according to claim 1, further comprising: atemperature detecting device that detects a temperature of the switchingelements of both substrates of the pair of substrates, wherein thetemperature detecting device is provided for the switching element ofthe substrate of the pair of substrates arranged on a downstream side ofthe coolant flow direction.
 6. The semiconductor module according toclaim 1, wherein the switching element of the one of the substrates ofthe pair of substrates is arranged on the one side in the perpendiculardirection, and the switching element of the other substrate of the pairof substrates is arranged on the other side in the perpendiculardirection.
 7. The semiconductor module according to claim 1, wherein thepair of substrates is provided with one of a pair of a lower armswitching element and an upper arm switching element.
 8. Thesemiconductor module according to claim 7, further comprising: atemperature detecting device that is mounted on the lower arm switchingelement, wherein temperature detection is carried out for temperaturecontrol of the switching elements of both substrates of the pair ofsubstrates.
 9. The semiconductor module according to claim 1, whereinthe plurality of substrates includes six substrates, each substrateincluding one of the lower arm switching element and the upper armswitching element of each phase forming a three-phase AC invertercircuit is placed on the one surface of the base plate.
 10. An inverterdevice including the semiconductor module according to claim
 1. 11. Asemiconductor module comprising: a base plate; a plurality of substratesplaced on one surface of the base plate, with each substrate of theplurality of substrates including a switching element, a diode element,and a connection terminal area; and a parallel flow forming device thatforms parallel coolant flow paths that are provided so as to be incontact with the other surface of the base plate, wherein: the coolantflow paths are formed such that coolant flows in a coolant flowdirection, the switching element and the diode element are arranged inline in a perpendicular direction with respect to the coolant flowdirection, the switching element and the connection terminal area arearranged in positions differing in the coolant flow direction in each ofthe substrates, a pair of substrates of the plurality of substrates isarranged in series in the coolant flow direction, the connectionterminal area is arranged on a first side in the perpendicular directionfor one substrate of the pair of substrates and on a second side in theperpendicular direction for the other substrate of the pair ofsubstrates, the diode element is arranged on the second side in theperpendicular direction for the one substrate of the pair of substratesand on the first side in the perpendicular direction for the othersubstrate of the pair of substrates, the connection terminal area of atleast one substrate of the pair of substrates is arranged closer to aside that is between the pair of substrates with respect to theswitching element of the at least one substrate of the pair ofsubstrates, and the switching elements of the pair of substrates arearranged at different positions in the perpendicular direction.
 12. Thesemiconductor module according to claim 11, wherein the pair ofsubstrates have an identical structure with each other and are arrangedto be symmetrical.
 13. The semiconductor module according to claim 11,wherein both of the connection terminal areas of the pair of substratesare arranged closer to the side that is between the pair of substrateswith respect to the switching elements of each substrate.
 14. Thesemiconductor module according to claim 11, wherein the parallel flowforming device is a plurality of fins arranged parallel with each otheralong the other surface of the base plate.
 15. The semiconductor moduleaccording to claim 11, further comprising: a temperature detectingdevice that detects a temperature of the switching elements of bothsubstrates of the pair of substrates, wherein the temperature detectingdevice is provided for the switching element of the substrate of thepair of substrates arranged on a downstream side of the coolant flowdirection.
 16. The semiconductor module according to claim 11, whereinthe switching element of the one of the substrates of the pair ofsubstrates is arranged on the one side in the perpendicular direction,and the switching element of the other substrate of the pair ofsubstrates is arranged on the other side in the perpendicular direction.17. The semiconductor module according to claim 11, wherein the pair ofsubstrates is provided with one of a pair of a lower arm switchingelement and an upper arm switching element.
 18. The semiconductor moduleaccording to claim 17, further comprising: a temperature detectingdevice that is mounted on the lower arm switching element, whereintemperature detection is carried out for temperature control of theswitching elements of both substrates of the pair of substrates.
 19. Thesemiconductor module according to claim 11, wherein the plurality ofsubstrates includes six substrates, each substrate including one of thelower arm switching element and the upper arm switching element of eachphase forming a three-phase AC inverter circuit is placed on the onesurface of the base plate.
 20. An inverter device including thesemiconductor module according to claim 11.